django-etcd-settings

Goal

This application allows you to extend the Django settings as configured in the settings.py file with:

• Environment dependent values
• Values in different config sets, identified by name, which can be selected on a 'per request' basis using the X-DYNAMIC-SETTINGS HTTP header

Installation

For now, just install it by pointing to this repository. You can either:

1. Clone this repository and run make test to check the library out and contribute to it

2. Have your Django application depend on this by using something like this in your requirements.txt file: https://github.com/kpn-digital/django-etcd-settings.git/kpn-digital/django-etcd-settings.git@master#egg=etcd_settings

Compatibility

This application has been tested with Python 2.7 and Django 1.7

Configuration

This Django application uses the following configuration keys:

• DJES_ETCD_DETAILS: a dict with 'host', 'port', 'protocol', 'prefix', 'long_polling_timeout' and 'long_polling_safety_delay' (both in seconds). 'prefix' is a string to be used as base path for all configuration managed by this app. i.e. '/config/api' will result in '/config/api/' and '/config/api/extensions/' to be used for environment defaults and config_sets respectively Timeouts default to 50 and 5 seconds respectively. If DJES_ETCD_SETTINGS is None, this app will start with no errors and etcd_settings.settings will resolve to django.conf.settings plus your DJES_DEV_PARAMS overwrites i.e.

  ETCD_DETAILS = dict(
      host='localhost', port=4000, protocol='http',
      long_polling_timout=50, long_polling_safety_delay=5
  )
  

• DJES_DEV_PARAMS: A module with local overwrites, generally used for development. The overwrites must be capitalized module attributes. These overwrites will have preference over development settings on ETCD, but not over configset overwrites indicated by the X-DYNAMIC-SETTINGS HTTP header

• DJES_ENV: A string with the name of the environment in which the code is running. This will be used for accessing the env_defaults in ETCD in a directory with that name i.e. 'test', 'staging', 'prod'...

• DJES_REQUEST_GETTER: path to a function which accesses the HTTP request object being handled. Ensuring access to this value can be implemented with, for instance, middleware. This settings is only used to allow config overwrites on runtime based on predifined config_sets. In case you don't want to use this functionality, just set this setting to None i.e. 'middleware.thread_local.get_current_request'

• DJES_WSGI_FILE: path to the wsgi.py file for the django project. If not None, the monitoring of environment configuration will perform a touch of the file everytime the env_defaults are updated, so that all processes consuming settings from django.conf can consume the latest settings available as well The path can be absolute or relative to the 'manage.py' file. i.e. /project/src/wsgi.py, wsgi.py

Then, add etcd_settings to the list of INSTALLED_APPS before any other that requires dynamic settings.

From your code, just do from etcd_settings import settings instead of from django.conf import settings.

In case you want to use etcd_settings to modify some values in your standard Django settings.py file (i.e. Database config), you can use the following snippet in your settings file, as high as possible in the file and immediately under the DJES_* settings definition:

import etcd_settings.loader
extra_settings = etcd_settings.loader.get_overwrites(
    DJES_ENV, DJES_DEV_PARAMS, DJES_ETCD_DETAILS)
locals().update(extra_settings)

TODO

• Extending the unit tests in order to cover etcd_settings.proxy and more of etcd_settings.manager

• Moving this repository to Github and updating url and download_url in setup.py file with the new repo location

• Uploading this package to PyPi. A user needs to be configured in .pypirc. After that, run:

  UPLOAD_TARGET=<upload_target> make upload
  

  ... where upload_target is one of pypitest or pypi